Field of the Invention
The present invention relates to a technique for assisting an analysis of behaviors of an energy plant including supply facilities that supply energy such as electricity, gas, heat or the like, and a consumption facility that performs air-conditioning, uses steam, and drains or delivers water, or the like by consuming the energy.
Description of the Related Art
For example, as disclosed by Japanese Laid-open Patent Publication No. 2001-273006, a technique for simulating behaviors of a plant on the basis of characteristics and a system diagram of component devices of the plant, and for performing an energy analysis in the use of the plant that consumes energy when being operated is conventionally known.
According to the technique disclosed by Japanese Laid-open Patent Publication No. 2001-273006, device objects that define basic setting values of component devices of an energy plant are accumulated for an operation evaluation system of the energy plant the operations of which are evaluated. Then, plant system diagram using the device objects are drawn, and setting values of component devices of the plant, and a connection relationship between the devices are extracted from the drawn plant system diagram, and are converted into a plant model. The plant model is used as an indicator with which the plant is evaluated and optimally operated.
Additionally, for example, as disclosed by “Algorithms of Quantifier Elimination and their Applications-Optimization by Symbolic and Algebraic Methods”, H. Anai, K. Yokoyama, University of Tokyo Press, 2011, pp. 214-221, a technique for expressing a problem such as a system control, a circuit analysis or the like by using a first-order predicate logical expression, and for optimizing the system by solving the first-order predicate logical expression is also known.
Specifically, a first-order predicate logical expression is obtained with a combination of a quantifier represented as a universal quantifier (∀) or an existential quantifier (∃), and a logical expression obtained by merging multi-variable polynomial equations and inequalities with the use of a logic symbol represented as a product (∧) or a sum (∨). A variable bound with a quantifier among variables that appear in a logical expression is called a bound variable, while a variable that is not bound with a quantifier is called a free variable. A logical expression to be satisfied by free variables is derived by eliminating bound variables in a first-order predicate logical expression, so that the system is optimized.
For example, Japanese laid-open Patent Publication No. HEI11-328239 also discloses, as a known technique, a technique for performing a control system design and a control system analysis with the use of a quantifier elimination method. With this technique, a control system analysis/design apparatus formulates constraints of an input control problem into a linear matrix inequality (LMI) or a bilinear matrix inequality (BMI). Then, constraints, represented as an LMI or a BMI, of design specifications or the like are transformed into a constraint formed by ORing inequalities, so that a control system is converted into a first-order predicate logical expression. Then, the control system is analyzed on the basis of the expression from which variables assigned a quantifier are eliminated.
For example, as disclosed by “Visualization of Optimal Supply and Demand Balance by Quantifer Elimination Approach”, Y. Tange, S. Kiryu, T. Matsui, Y. Fukuyama, Society of Instrument and Control Engineers, Symposium on Measurement Automated Control Society Control Department, 13th ROMBUN No. 8C2-5, a technique for analyzing the energy of a plant is also known. With this technique, a first-order predicate logical expression is generated, and an energy analysis can be performed by solving the first-order predicate logical expression.
As described above, the technique for analyzing behaviors of a plant by generating a first-order predicate logical expression and by solving the expression with a quantifier elimination method is a known technique. However, operations for setting a first-order predicate logical expression are not easy in general unless a user is an expert. Namely, with this conventional technique, a user needs to write a target problem by using a first-order predicate logical expression, and to determine how to assign a quantifier to each variable. Accordingly, it is difficult for a user who has no expertise to use the method of analyzing behaviors of a plant by generating a first-order predicate logical expression and solving the expression, although this is helpful means for an analysis.
Additionally, there is a demand for evaluating a plant in each of various cases assumed when the plant is evaluated. Examples of such cases are where a comparison is made between a case where a facility is operated and a case where the facility is stopped, a comparison is made between a case where an operation state of a facility is fixed and a case where the operation state is varied, a comparison is made between a case where the capability of a facility is not changed and a case where the capability is changed, and a comparison is made between a case of the current operation state of a plant and a case of a predicted future state.